A disk drive, such as a magnetic disk drive, comprises a magnetic disk, a spindle motor, a magnetic head, and a carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the magnetic disk. The magnetic head reads data from and writes data to the magnetic disk. The carriage assembly supports the magnetic head for movement relative to the magnetic disk. The carriage assembly includes a rotatable arm, and a suspension extending from the arm. The magnetic head is supported on the extended end of the suspension. The magnetic head includes a slider attached to the suspension, and a head section on the slider. The head section comprises a recording head for writing and a read head for reading.
Magnetic heads for perpendicular magnetic recording have recently been proposed in order to increase the recording density and capacity of a magnetic disk drive or reduce its size. In one such magnetic head, a recording head comprises a main pole producing a perpendicular magnetic field, return or write/shield pole, and coil. The return pole is located on the trailing side of the main pole with a write gap therebetween and closes a magnetic path that leads to a magnetic disk. The coil serves to pass magnetic flux through the main pole.
When recording a recording pattern along a track of the magnetic disk, a recording magnetic field also leaks from both sides of the main pole in the track width direction. To reduce this leakage magnetic field, a magnetic head having side shields provided on both sides of the main pole in the track width direction has been suggested.
In the magnetic head having the side shields, erase width control effected by the side shields can be expected. However, when repeatedly performing the recording operation on the same track, recorded information may be erased or deteriorated in a wide region of several tens of tracks because of a return magnetic field immediately below the side shields in a magnetic flux distribution returning to the return pole from the main pole through a soft magnetic layer below a recording layer of a perpendicular recording medium.
Further, when an interval between the side shield and a side surface of the main pole is wide, there may possibly occur a phenomenon that recorded information in an adjacent track is erased or deteriorated because of magnetic flux originating from a narrowed portion of the main pole to the medium, and hence track density cannot be improved.